The present invention relates to a double-headed piston type compressor provided with rotary valves on both ends of a rotary shaft.
As a vehicle air-conditioning compressor, a double-headed piston type compressor has been in use, for example. In the compressor of this kind, each of a plurality of double-headed pistons is housed in a pair of front and rear cylinder bores. A housing of the compressor has a swash plate chamber for accommodating a swash plate which rotates with a rotary shaft. Rotation of the swash plate reciprocates the double-headed pistons within the cylinder bores. The double-headed piston defines a compression chambers in the cylinder bore. Along with the reciprocation, the double-headed piston draws refrigerant into the compression chambers via a refrigerant suction system. The double-headed piston also compresses the refrigerant in the compression chambers and then discharges the refrigerant to discharge chambers.
The refrigerant having been discharged into the discharge chambers is delivered to an external refrigerant circuit via piping. The refrigerant having passed through the external refrigerant circuit is sent back to the compressor via piping. Japanese Laid-Open Patent Publication No. 5-306680 discloses a refrigerant suction system allowing a refrigerant to be drawn from a swash plate chamber to a compression chamber via a rotary valve. Japanese Laid-Open Patent Publication No. 2003-222075 discloses a refrigerant suction system allowing a refrigerant to be drawn from a suction chamber formed in a housing of a compressor to a compression chamber via a rotary valve.
In the compressors disclosed in the above-mentioned Japanese Laid-Open Patent Publication No. 5-306680 and Japanese Laid-Open Patent Publication No. 2003-222075, however, pulsations (pressure fluctuations) are caused when the refrigerant is drawn into the compression chambers via the rotary valve. The pulsations resonate an external device such as the piping or the external refrigerant circuit, whereupon noise can be caused in a passenger compartment.